Overdrive conversion unit and method of using same



Feb. 25, 1964 c. E. SHOOK ETAL 3,122,029

OVERDRIVE CONVERSION UNIT AND METHOD OF USING SAME 2 Sheets-Sheet 1Filed May 25, 1961 (BEE/A SM/m',

Claws-was SHOOM,

INVENTORS.

Feb. 25, 1964 c. E. SHOOK ETAL 3,122,029

OVERDRIVE CONVERSION UNIT AND METHOD OF USING SAME Filed May 25, 1961 2Sheets-Sheet 2 Hid-22$ afiRE/VCE 5PM,

1N VEN TORIS,

I BY 453mm (1% 4rruaurx United States Patent 3,122,029 OVERDREJECGNVERSIGN UNET AND METHOD OF USINfI SAME Clarence E. Shook, Lakewood,Calif. (6309 Paramount Blvd, Long Beach 5, Calif), and Basil E. Smith,El Monte, Calif. (2118 N. Lee, South El Monte, Calif.) Substituted forabandoned application Ser. No. 743,559, June 23, 1958. This applicationMay 25, 1% Ser. No. 116,912

2 Claims. (Cl. 74-606) The present invention relates generally to thefield of automotive equipment, and more particularly to an apparatus andmethod of using the same by which it is possible to convert a four-wheeldriven vehicle to include an overdrive.

As is well known, a four-wheel drive automotive vehicle is ideallysuited for traveling over rough, hilly country such as is frequentlyencountered in fishing and hunting expeditions. However, onedisadvantage of such vehicles is that they have a limited top speed, andtherefore are not suited for traveling on modern highways for longdistances. In the past, this disadvantage has restricted four-wheeldrive vehicles to specific and restricted uses, rather than for allround use thereof.

A major object of the present invention is to provide an apparatus andmethod of using the apparatus by which a four-wheel drive vehicle can beconverted to include an overdrive, even if the transmission of thevehicle is short-coupled.

Another object of the invention is to provide an apparatus and method ofusing the same that will give the four-wheel drive vehicle on which theapparatus is installed greater versatility of use, and permit thevehicle to be driven at high speed over a highway prior to its use intraveling over rough and hilly terrain.

Yet another object of the invention is to supply an apparatus that is ofsimple mechanical structure which can be installed without difficulty ina four-wheel drive vehicle, and which is so inexpensive to produce thatit can be sold at a sufficiently low price as to encourage itswidespread use in the conversion of four-wheel drive vehicles to includean overdrive.

These and other objects and advantages of the invention will becomeapparent from the following description of a preferred form thereof, andfrom the accompanying drawing illustrating the same in which:

FIGURE 1 is an elevational view of a four-wheel drive vehicle which ispartially cut away to show the disposition of overdrive conversion;

FIGURE 2 is a bottom view as indicated by the arrows 2-2 in FIGURE 1;

FIGURE 3 is an enlarged plan view of the conversion, partially insection, taken on line 33 of FIGURE 1;

FIGURE 4 is an elevational view taken on line 44 of FIGURE 3 showing theadapter plate; and

FIGURE 5 is an elevational view in complete detail of the specialconversion drive shaft.

Referring now to the drawings for the general arrangement of theinvention, a four-wheel drive vehicle is shown in FIGURES 1 and 2 whichincludes a frame portion F. Suspended on or fixedly secured thereto isthe main transmission housing T. The geared power transfer mechanism iscarried in the transversely disposed housing 143 and from the forwardend thereof extends the standard drive shaft providing the power meansfor the standard front wheel drive. This conventional drive mechanismhas been designated generally as FWD. From the rear of said transferhousing the standard drive shaft 11 normally extends in conventionalmanner to the differential DF providing power to the rear wheels of thevehicle.

In the small space between the transfer housing 10 and 3,122,029Patented Feb. 25, 1964 differential DE, a special mechanism has beenprovided for adapting a conventional overdrive to said elements. Toaccomplish this end, the standard emergency brake mechanism (not shown)is removed, which is usually carried on the standard drive shaft 11immediately adjacent the rear face 12 of the transfer housing 10. Thestandard dual-splined, longitudinally disposed short drive shaft in thehousing 10 is removed and a special adapter plate 13, shown in FIGURES 3and 4, is securely attached thereto about the drive shaft opening 14 inthe rear of housing 10. Adapter plate 13 is a rugged, thick steelelement connected to the rear face 12 of the transfer housing 10 in thefollowing manner.

Plural openings 15 are drilled in adapter plate 13 to coincide withthreaded bores 16 in the rear face 12 of transfer housing 10. Openings15 are countersunk at 17 to receive plural, rugged screw-headedattachment pins 18, threaded at 18a to engage said threaded bores 16.Plate 13 has a central aperture 19 formed therein that coincides withthe standard drive shaft opening 14 in the transfer case or housing 10.A circumferential recess 20 is machined about said aperture 19 on theouter face of plate 13, and provides a centering and receiving portionfor a cylindrical boss 21 specially machined on the attachment plate orinner end casting 22 of a conventional overdrive mechanism 0 from whichthe standard driving element or shaft and the inner shaft-bearingsupport have been removed. The inner face of adapter plate 13 has dualrecesses 23 and 24 respectively formed therein which receive theslightly projecting front face of a standard bearing 25 of transfer case1%.

A specially designed and machined driving power connecting element isprovided that unites and becomes common to both the power transfermechanism and the conventional overdrive. Machined on the inner end ofthe power connecting element or drive shaft, designated generally D5,are the dual standard gear connecting splined portions 26 and 27respectively. The outer end of drive shaft DS is machined to conformexactly to the standard worm 28 and splined portion 29 of the shaftpreviously removed from the overdrive mechanism 0. The plate or casting22 of the overdrive mechanism 0 is attached to adapter plate 13 by meansof four threaded bolts 30 which pass through plural apertures 31 inplate 22 of the overdrive and are received in plural threaded bores 32in attachment plate 13.

The actual disposition of the combined power connect ing and drive shaftmember DS is best shown in FF"- URE 3. It will be noted that theassociation of relative parts and centering of the adapter plate 13 andattachment plate 22 by means of the recess 20 and boss 21 actuallyresults in perfect alignment of the special shaft DS in standard bearing25 in the transfer casing 10 and a conventional bearing 34 in theoverdrive mechanism. The drive shaft 11 operatively connected to therear differential mechanism DF is shortened in such manner that it canbe connected by a universal joint 36 to the attachment coupling 37 onthe outer end of the overdrive mechanism.

As far as the operation of the device is concerned, it is believedobvious from the above description that there has been no changewhatsoever affecting the normal fourwheel drive transmission means andthat when the overdrive mechanism has been adapted to the transfer meansand rear wheel drive the four-wheel drive vehicle will have greatlyimproved road characteristics on the open highway.

Although our invention is fully capable of achieving the results andproviding the advantages hereinbefore mentioned, it is to be understoodthat it is merely the presently preferred embodiment thereof, and we donot meanfto be limited to the details of construction above describedother than as defined in the appended claims.

We claim:

1. A four-Wheel drive automotive vehicle having a transmission, powertransfer unit, differential and difierential drive shaft that ischaracterized by an overdrive conversion unit associated therewith, saidunitconsisting of: an apertured adapter plate secured to the powertransfer mechanism thereof, said plate having a centering recess shafthaving dual splined portions at one end thereof conforming to butreplacing the removed originally provided power transfer drive shaft,the opposite end of said adapter drive shaft being machined t0 overdriveform and dimensions; and an overdrive mechanism operatively re- 15-ceiving said overdrive endof said adapter shaft, said overdrivemechanism having an inner'attachment face for machined therein; anadapter power-transferring drive 10 ing and said overdriveattachmentface is fixedly connected to said adapter plate.

References Cited in the file of this patent .7 UNITED STATES PATENTS2,811,049 1 2,835,143 Kelbel e May 20, 1958 2,936,648 Barnes May 17,1960 Dennis Oct. 29, 1957

1. A FOUR-WHEEL DRIVE AUTMOTIVE VEHICLE HAVING A TRANSMISSION, POWERTRANSFER UNIT, DIFFERENTIAL AND DIFFERENTIAL DRIVE SHAFT THAT ISCHARACTERIZED BY AN OVERDRIVE CONVERSION UNIT ASSOCIATED THEREWITH, SAIDUNIT CONSISTING OF: AN APERTURED ADAPTER PLATE SECURED TO THE POWERTRANSFER MECHANISM THEREOF, SAID PLATE HAVING A CENTERING RECESSMACHINED THEREIN; AN ADAPTER POWER-TRANSFERRING DRIVE SHAFT HAVING DUALSPLINED PORTIONS AT ONE END THEREOF CONFORMING TO BUT REPLACING THEREMOVED ORIGINALLY PROVIDED POWER TRANSFER DRIVE SHAFT, THE OPPOSITE ENDOF SAID ADAPTER DRIVE SHAFT BEING MACHINED TO OVERDRIVE FORM ANDDIMENSIONS; AND AN OVERDRIVE MECHANISM OPERATIVELY RECEIVING SAIDOVERDRIVE END OF SAID ADAPTER SHAFT, SAID OVERDRIVE MECHANISM HAVING ANINNER ATTACHMENT FACE FOR CONNECTION WITH SAID ADAPTER PLATE, SAID FACEBEING MACHINED TO FORM A BOSS ENGAGING SAID ATTACHMENT PLATE CENTERINGRECESS AND THUS ALIGNING SAID ADAPTER SHAFT TO EXCLUDE THE USE OF ANORIGINAL PROVIDED FRONT BEARING ELEMENT, SAID OVERDRIVE MECHANISM AT ITSOUTER END BEING CONNECTED TO A SHORTENED END OF SAID DIFFERENTIAL DRIVESHAFT.